红外吸收光谱型城市路网尾气浓度检测传感器

为了能够集中测量城市路网中CO、NO、NO2和SO2的浓度,利用红外吸收光谱原理和谐波调制技术设计了四向气体浓度检测传感器。将宽带光谱LED作为共用光源,穿过四个方向上特定波长的窄带滤光片后,产生与被测气体吸收光谱一致的光束,再穿过改进的Herriott型长光程吸收气室,并在红外探测器上感应出电信号,最后利用设计的正交锁相放大电路测量出二次谐波系数大小,从而计算出被测气体的浓度。实验结果表明:设计的传感器输出的电压与被气体浓度呈正比例线性关系,平均线性度达到了0.997 85,测量误差均小于2%,可为播报环境质量和制定机动车尾气排放标准提供数据支持。

Infrared Absorption Spectrum Sensor for Detecting Exhaust Gas Concentration in Urban Road Network

To intensively measure the concentration of CO,NO,NO2 and SO2 in urban road network,a four-way gas concentration sensor is designed based on the principle of infrared absorption spectrum and harmonic modulation technology. The wide band spectral LED is used as a common light source,and four beams consistent with the measured gas absorption spectrums are generated after passing through narrowband filters with specific wavelength in four directions. Then,the four beams pass through the improved Herriott type long-path absorption chamber,and the electrical signal is inducted on the infrared detector. Finally,the second harmonic coefficients are measured using the designed quadrature phase-locked amplifier circuit so as to calculate the concentration of the measured gas. The experimental results show that the output voltage of the designed sensor is proportional to the concentration of the gas,the average linearity of the sensor is 0.997 85 and the measurement error is less than 2%,which can provide data support for broadcasting environmental quality and formulating the vehicle exhaust emission standards.